<div class="content">
  <div class="list">
    <div class="item">
      <div class="content">
        <div class="article">
          <p>参考：</p>
          <ul>
            <li><a target="_blank" href="http://www.w3schools.com/howto/howto_css_switch.asp">http://www.w3schools.com/howto/howto_css_switch.asp</a></li>
          </ul>
        </div>
      </div>
     </div>
  </div>
</div>
